[RUM dashboard] filter capabilities

[katrin-freihofner]

Describe the feature:
One of the biggest problems with RUM data is that the experiences within it are so variable based on what cohort they belong to, that you really need to break down the data to get actionable insight. Therefore we are going to introduce the filter bar for our new RUM dashboard view.

Filter options

• Urls: Multi-select, default: "All URLs"
• Locations: Multi-select, default: "All locations"
• Devices: Multi-select, default: "All devices"
• Operating system: Multi-select, default: "All operating systems"
• Browser: Multi-select?, default: "All browsers"; can select browser family (for example Chrome) but also a specific version

@drewpost can you please verify this?

Design ticket

[elasticmachine]

Pinging @elastic/uptime (Team:uptime)